Distribution transformers are conveniently suspended from the tops of supports, such as utility poles or other isolated locations. In these positions, they are elevated away from intermeddling and are immediately adjacent the primary and secondary electrical circuits that they serve. Consequently, such transformers, once installed, remain in place for many years. Thus, it is of particular importance that the original transformer manufacture be of integrity and that these relatively large, heavy objects--in the range of up to 4,000 pounds--be both easy to install and remain installed during the entire service life of up to 30 or 40 years.
Such distribution transformers are contained within a tank, which tank can either be round or square. These transformers can vary; they can include conventional single phase or three phase transformers. Consequently, the tank is in turn provided with a regulation mandated nameplate and brackets. The function of the nameplate is to identify the transformer. This information must be easily available to elevated line personnel effecting connection, and routing of power from the transformer. Since changes in connections and routing of power occur during the relatively long service life of the transformer, the nameplate information display must last as long as the service life of the transformer.
Installation of nameplates to such distribution transformers constitutes a difficulty. Nameplates are now commonly affixed directly to the tank sides. Mounting brackets have not been utilized for the placement of the nameplates. Due to the configuration of the sides of prior art brackets utilized to affix distribution transformer tanks to these supports, the dimension of the side of the bracket is insufficient to accommodate the dimension of the regulation mandated nameplate.
Affixing the nameplate data to the tank sides is not as simple as it sounds. Specifically, it is required that the nameplate remain affixed to the tank sides during the full in-service life of the transformer. It is further required that the nameplate not interfere with the integrity of the tank. For example, it cannot be a point of attachment where the paint surface of the tank is interrupted. This being the case, there is a surprising elaboration of detail devoted to the simple task of adhering the nameplate to the tank.
In one commonly used solution, a separate and discrete nameplate bracket is first attached to the tank. This discrete tank mounted nameplate bracket is paint protected. Thereafter, the nameplate is attached to the bracket. Thereafter, the nameplate is bent to gain access and paint protection applied to the bracket and nameplate to insure both permanence of the nameplate and corrosion protection of the tank during the full in service life of the distributing transformer.
Having set forth the problem with nameplates, attention can now be turned to those problems directly associated with the mounting brackets themselves.
These mounting brackets constitute the support points to the supporting transformer tank as well as the connection to the support, such as a utility pole. These brackets must be securely welded to the tank. The brackets must have static and dynamic properties to maintain the supported transformers to the supports under the worst possible conditions that can occur in their long in service life. For example, one standard requires that the brackets be able to withstand five times the weight of the distribution transformer without tearing of the metal of the brackets.
Required testing of such brackets is not trivial. Brackets are tested to destruction. Further, one bracket is assumed to support the entire load. This being the case, this one bracket is required to withstand the five times weight requirement of the required support. Further, although the brackets are permitted to deform during such tests, tearing of the metal of the brackets is not permitted.
These brackets must be painted--inside and out--to accommodate the longest possible service life of the transformer against possible corrosion. Finally, the brackets must make the installation and removal of the transformers as facile as possible. Bearing in mind that line personnel are usually at the top of a utility pole, hanging out on a climbing belt, manual tasks such a fixing the bracket to the pole must be facilitated by the design of the bracket.
Present brackets have remained unchanged for many years. All known brackets include a truncated rectilinear frame member having two parallel sides. In one embodiment--see FIGS. 2A and 2B--a bracket piece is separately and discretely welded onto a linear piece connecting the two parallel sides to form the bracket bolt anchorage to the utility pole. In another embodiment, the linear member connecting the two side is bent along four substantially 90.degree. fold lines to form the bracket bolt anchorage to the utility pole.
It will be understood that distribution transformers are each hung by two such brackets from the tank sides. Typically, one bracket is a top bracket and the other bracket is a bottom bracket placed directly under the top bracket. Usually, the top bracket has a "jump proof lip" for hanging onto the bolt or bracket to which the transformer is mounted. The lower bracket is usually conventional and does not include the jump proof lip. Thus, where there is a dynamic loading on the transformer mount, the jump proof lip prevents the transformer from moving upwardly and free of its attachment to the pole mounted bolt or bracket.
Both bracket types have similar deficiencies.
First, and with regard to both brackets, attachment to the tank occurs by a butt weld. Specifically, the end piece of metal of the bracket abuts the rounded surface of the tank. Typically, each side of the bracket is tack welded in place and the butt weld completed by welding around the plane of abutment with discrete top, outside, bottom and remaining inside the bracket welding passes. The bracket itself often obstructs and renders inconvenient these welding passes, especially the inside welding passes. While such attachment is secure, it is only as strong as the butt point of abutment of the bracket.
Secondly, and once the brackets are attached, corrosion protective paint must be applied. Again, the configuration of the bracket obstructs access--primarily on the inside--for proper painted protection against the possible years of weathering corrosion during in-service life.
Assuming that the brackets are properly installed, the transformer is then hoisted for installation at the top of a utility pole. In such installation, access to the interior of the attached hanger brackets is required by the line personnel, typically hanging out at the ends of their working belts directing the lowering of the transformers and simultaneously attaching the brackets to the poles. In such attachment, turning of attaching bolts is required from the inside of the brackets. Unfortunately, the brackets of the prior art at their access restricting sides only serve to restrict such attachment. Sufficient space is not provided to allow the wrenches to "see" the bolts for secure attachment. Rotation of bolts interior of the brackets is restricted to small, discrete, repetitive increments of rotation consuming both the time and effort of the elevated line personnel.
After compiling the foregoing information, a new distribution transformer tank bracket has been developed. This design happens to address all of the above recited shortcomings.